The present invention relates to a storage assist device for vehicle seat. More particularly, it relates to a storage assist device for vehicle seat that is rotatable in a front and rear direction in a state where a seat back is folded onto a seat cushion.
Conventionally, in a vehicle provided with rear seats such as the second-row or the third-row seat, there is known a vehicle seat which is rotated to the rear of the vehicle seat that is stored in a storage recess portion formed in a vehicle body floor in a state where the rear ends of a seat cushion constituting the vehicle seat is rotatably supported in the front and rear direction in front side of the storage recess portion and the seat back is folded onto the seat cushion.
Generally, in such a vehicle seat, when it is moved from a use position to a storage position, or when it is moved from the storage position to the use position, the vehicle seat is rotated as a heavy object around a rotating shaft. Therefore, the strong operation force in a rotating direction of the vehicle seat is required until the center of gravity of the vehicle seat reaches on a vertical surface including the rotating shaft, and, after it reaches thereon, the operation force for storing the vehicle seat while suppressing an increase in a rotational speed of the vehicle seat by its own weight is required, so that the vehicle seat had low operability.
Then, for example, there has been proposed a storage assist device provided with a torsion spring that accumulates a restoring force on a rotating shaft attached to a seat cushion, in both cases when a vehicle seat is moved from a use position to a storage position and moved from the storage position to the use position (refer to Japanese Unexamined Patent Application Publication No. H06(1994)-144092 (“the '092 Publication”)).
According to such a storage assist device, in both cases when the vehicle seat is moved from the use position to the storage position and moved from the storage position to the use position, since the operation of the vehicle seat can be assisted by the restoring force of the torsion spring, it is possible to reduce the operation load and the rotational speed of the vehicle seat (hereinafter referred to as “the rotating operation force of the vehicle seat”).
However, in the storage assist device described in the '092 Publication, since the reduction of the rotating operation force of the vehicle seat is achieved by the urging force of the torsion spring, in a case where the urging force of the torsion spring is strong, the operation load of the vehicle seat can be reduced, but after the center of gravity of the vehicle seat reaches on the vertical surface including the rotating shaft, the vehicle seat stops in the middle of rotating in a raised state, which poses a problem in that the seat must be further pushed strongly to be in the storage position or the use position. Particularly, such a state causes a disadvantage in that the vehicle seat is rattled by vibrations during the vehicle running for example, in a state where the vehicle seat is moved to the storage position.
Such a disadvantage can be resolved by setting the urging force of the torsion spring weakly, but in this case, the operation load of the vehicle seat cannot be reduced sufficiently, and after the center of gravity of the vehicle seat reaches on the vertical surface including the rotating shaft, a disadvantage in that the rotational speed by its own weight of the vehicle seat cannot sufficiently be controlled is caused.
Thus, in the storage assist device described in the '092 Publication, the urging force of the torsion spring must be adjusted upon consideration of weight and the like of the vehicle seat, which poses a problem in that the adjustment thereof is very complicated.
Further, in the above-described storage assist device, the torsion spring is stored within a bracket for supporting the rotating shaft rotatably, which poses a problem in that the installation and the replacement of the torsion spring are very complicated.